Handheld Sound and Vibration FFT Analyzer

FFT Analysis and Tone Assessment | Model 831C-FFT

831C-FFT sound level meter for fast fourier transform analysisWhen higher frequency resolution than 1/3 octaves is needed, FFT Frequency Analysis Model 831C-FFT is the ideal solution. The narrow-band filtering provided by Fast Fourier Transform (FFT) Analysis of single-channel acoustic or vibration sources is useful for machinery analysis, product development, tone detection, fault analysis, and vibration troubleshooting. Offering precision spectral analysis of signals, FTT acquisition settings can be adjusted to visualize specific acoustic and vibration phenomena. Using FFT on the handheld SoundAdvisor™ Sound Level Meter is a convenient way to achieve an objective measurement of tones or vibration phenomena in the field.

Already own a SoundAdvisor Meter or System? Turn your Sound Level Meter into an FFT analyzer without returning it to the factory by adding Model 831C-FFT Firmware using G4 LD Utility Software.

FFT Sound and Vibration Analysis Applications

  • Hand-held, single-channel FFT measurements
  • In-field tone detection and assessment
  • Noise source identification
  • Harmonic Analysis: Total Harmonic Distortion (THD and THD+n)
  • Consumer product testing
  • Machinery troubleshooting
  • Building vibration analysis
  • Automotive component analysis

FFT Analysis, Simplified

  • Connect a microphone or single channel ICP® vibration sensor
  • Onboard computation of tonality as described in ISO/PAS 20065:2016*, and ISO 1996-2 Annex C
  • Support for Engineering Units
  • Real-time data on the meter, mobile device, or PC
  • No-license LD Atlas™ (mobile app) and  G4 LD Utility (PC software)
  • View and archive data and post-process results in app or software
  • Auto peak finding with harmonic cursors
ICP Cable Adaptor Model ADP074


  • ICP Cable Adaptor Model ADP074: Mates ICP single axis accelerometer to SoundAdvisor Sound Level Meter providing 4 mA ICP input on BNC connector
FFT Analysis (with option 831C-FFT) Technical Specifications

FFT Lines

400, 800, 1600, 3200, & 6400

Bandwidth (Hz)

100, 200, 500, 1k, 2k, 5k, 10k, & 20k


Hanning, Flat-top, and Rectangular


Fixed 33%


dB re 20 uPa, m/s2, cm/s2, mm/s2, g, ft/s2, in/s2, custom


Linear or log


Max tracking with harmonic cursors

Supported Sensors

Microphone or ICPr accelerometer (with ADP074)


Frequency domain to velocity and displacement

Acoustic weighting

A, C, or Z (none)


ISO/PAS 20065:2016 Acoustics - Objective method for assessing the audibility of tones in noise - Engineering method